Image sensor having a photoelectric conversion layer coupled to a storage node through a pinning layer with P-type impurities
An image sensor includes a first photoelectric conversion layer that is configured to convert light to a first signal. The image sensor also includes a transfer transistor. The transfer transistor includes a storage node region which stores the first signal. The transfer transistor also includes a transfer gate which transfers the stored first signal, and a floating diffusion region that receives the first signal. The image sensor includes a reset transistor that resets the floating diffusion region, and a drive transistor which receives a pixel voltage. The drive transistor generates an output voltage. The image sensor also includes a selection transistor which outputs the output voltage. A reset drain voltage is applied to a drain electrode of the reset transistor, and is independent of the pixel voltage. The reset drain voltage ranges from about 0.1V to about 1.0V.
1. An image sensor comprising:
an active pixel sensor array including a first pixel; and
a substrate on which the active pixel sensor array is disposed,
wherein the substrate includes a first surface and a second surface facing each other, and wherein the substrate is configured to receive light at the second surface, and
the first pixel includes:
a first lower electrode disposed on the second surface, and configured to receive a first voltage;
a first photoelectric conversion layer disposed on the first lower electrode;
an upper electrode disposed on the first photoelectric conversion layer, and configured to receive a second voltage that is higher than the first voltage;
a first storage node region, a first floating diffusion region, a reset source region, and a reset drain region that are disposed in the substrate and adjacent to the first surface, wherein the first storage node region and the first floating diffusion region include n-type impurities, and wherein the first storage node region includes a pinning layer which is connected to the first photoelectric conversion layer and which includes p-type impurities;
a first transfer gate disposed on the first surface, and interposed between the first storage node region and the first floating diffusion region;
a reset gate disposed on the first surface, and interposed between the reset source region and the reset drain region; and
a first through via which is disposed through the substrate, and configured to electrically connect the first lower electrode and the first storage node region,
wherein the reset source region is electrically connected to the first floating diffusion region, and
a reset drain voltage ranging from about 0.1V to about 1.0V is applied to the reset drain region.
2. The image sensor of claim 1 , wherein the first pixel further includes a second photoelectric conversion layer which is disposed in the substrate.
3. The image sensor of claim 1 , wherein the reset drain voltage ranges from about 0.3V to about 0.7V.
4. The image sensor of claim 1 , wherein the first pixel further includes a source follower gate which is spaced apart from the first transfer gate on the first surface, and the source follower gate is configured to electrically connect to the first floating diffusion region.
5. The image sensor of claim 1 , wherein the first pixel further includes:
a second lower electrode which is spaced apart from the first lower electrode on the second surface, and configured to receive a third voltage that is lower than the second voltage;
a second storage node region and a second floating diffusion region that are disposed in the substrate, adjacent to the first surface, and spaced apart from the first storage node region and the first floating diffusion region;
a second transfer gate disposed on the first surface, and interposed between the second storage node region and the second floating diffusion region; and
a second through via disposed vertically through the substrate, connecting the second lower electrode with the second storage node region.
6. The image sensor of claim 1 , wherein the active pixel sensor array further includes a second pixel spaced apart from the first pixel, and
the second pixel includes:
a second storage node region and a second floating diffusion region that are disposed in the substrate, adjacent to the first surface; and
a second transfer gate disposed on the first surface, and interposed between the second storage node region and the second floating diffusion region,
wherein the second floating diffusion region is electrically connected to the first floating diffusion region.